Where do we need shade? Mapping Urban Heat Islands in Richmond City streets

Here is an excerpt from a recent study regarding urban heat vulnerability zones across the city

While the urban heat island effect is generally described as a city being warmer than the surrounding rural areas, heat intensity can also vary from neighborhood to neighborhood within a city. For example, dark surfaces such as asphalt absorb more heat than lighter surfaces, and built materials such as bricks and concrete absorb more heat than grass and vegetation. This means that some sections of a city will face higher temperatures on hot days than others. […]

On July 13, 2017, in the midst of Richmond’s first major heat wave of the summer, 15 teams of volunteers spread out through the city in cars and on bikes equipped with simple hand-made devices. Each device was designed to measure air temperature and mark time and location as it was moved along. By recording the temperature every second of each hour-long ride, and plotting those temperatures on a map, data from the devices could be used to generate a map of temperatures along each route over the entire city. Riders and drivers rolled through the heat on their assigned routes three times that day: at 6:00 am, at 3:00 pm, and again at 7:00 pm.

All temperature and location data collected by the teams were fed into an open-source software package developed by Shandas’ team at Portland State. Processing the data this way allows researchers to relate different types of land use to air temperatures, even across areas that weren’t directly measured. The resulting map showed a detailed picture of Richmond’s urban heat across the entire city.

The map showed differences of up to 16°F across Richmond’s neighborhoods during the hottest part of the day. This means that when a heavily shaded neighborhood in Richmond experiences an afternoon temperature of 87°F, it might reach 103°F in a more urbanized neighborhood in the same city. The data also revealed that warmer areas experienced a greater difference between morning and afternoon temperatures than did cooler areas.

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